1. Field of the Invention
The present invention relates to flexible building sheet products. More particularly, the present invention relates to a flexible building sheet product fabricated by a dry molding technique from a mixture of a binder component composed of at least one member selected from the group of thermoplastic resin emulsions and aqueous solutions containing a water-soluble polymer and a cross-linking agent for the polymer and a matrix component composed of calcium sulfate dihydrate powder.
2. Description of the Prior Art
It has been a conventional practice to finish the interiors of buildings with inorganic materials such as mortar and sand-based wall products. However, recently various other interior materials have also come into popular use in order to satisfy the need for a variety of decorations as well as the demand for lower engineering costs. The representative materials thus far available include wallpapers based upon woven fabrics, nonwoven fabrics, converted paper, and the like as well as predecorated plywood products.
In addition, recent demands have required that interior decorating materials should be noncombustible. While gypsum boards, asbestos boards, slates, and the like satisfy the nonflammability requirement, these materials are by no means considered to be decorative interior materials in the usual sense of the word, since they are used only in some ceiling applications.
In addition to the noncombustibility features, desired interior construction materials should satisfy many other requirements which include water resistance, moisture condensation resistance, abrasion resistance, bending workability, impact resistance, bonding qualities, stain resistance, sound absorbing properties, heat insulation, an attractive appearance and shade, and the like. No interior product has yet been developed which satisfactorily meets these requiements. On the other hand, building materials such as gypsum boards which possess improved water resistance and strength can be prepared by the addition of a reforming additive or modifier such as a water-soluble polymer, e.g., polyvinyl alcohol, ureaformaldehyde resin, or the like, and other additives to hydraulic gypsum as disclosed in Japanese Patent Publication No. 14840/69, Japanese Patent Application No. 26524/77, which was laid open to the Public, and Japanese Patent Publication No. 23786/63, for instance.
However, the building sheet product of the present invention is essentially unlike the hard and brittle products of hydraulic inorganic materials, but instead, is primarily based of calcium dihydrate and a water-resistant binder.